Files in this Data Supplement:

• Movie I - (Video Clip) (11.6 MB). Movie I is a time-lapse movie of a chick embryo in SC with normal vasculogenesis (with a rate of 5 frames per second). The image series starts with a day 2 chick embryo that was transferred in the early looping stage (48 hours after incubation) from its shell to a sterilized polystyrene weighing boat in a Petri dish with water and ends at the 9th day of recording, ie, 11 days after incubation. To create this movie, the embryo was moved every 60 minutes from the incubator to a special stage for visual registration with a digital camera (Canon PowerShot A80, Canon Inc). The recording starts at 8 AM; thus, the first image of the movie is labeled day 1, hour 8 (this applies also to Movies II through IV). At the end of the 7th incubation day, the interval between 2 subsequent visual recordings was stretched from 60 minutes to 120 minutes because the morphological changes of the embryos and their extraembryonic vasculature were not as dramatic compared with earlier stages. The movie depicts the complex process of vasculogenesis “outside” the embryo within the so-called extraembryonic membranes (EEMs) that occurs parallel to intraembryonic cardiovascular development. Note the dramatic change in vasculogenesis in EEMs during development over 9 days recording: at the beginning, compromising an area <2 cm; then growing further by sprouting in a hexagonal direction, adopting to the weighing boat; and after 6 days of recording, filling the whole weighing boat. There are 4 EEMs: the yolk sac, amnion, allantois, and chorion. At day 2 of embryonic chick development, only the yolk sac can be directly distinguished from the other 3 EEMs by the presence of blood vessels, called vitelline vessels. These vessels are directly visualized and prominent at the beginning of the movie. Later during development, the vitelline vasculature increases in amount and size and spreads over the whole yolk sac, which in turn starts to fill the weighing boat at about day 6 of recording. Note the development of the allantois near the lower part of the embryo toward the end of day 2 of recording, although it becomes clearly visible starting at day 4 of recording by changing from a saclike structure to an outgrowing compound of new vessels. These are vessels of the chorion-allantois membrane and increase their caliber size significantly from the recorded day 6 on, covering more and more the whole growing embryo and the vitelline vessels, forming a secondary vessel layer. Note the compensatory slight retraction and decrease in size of the vitelline vessels from day 6 to 9 of recording by normal development of the growing embryo.
• Movie II - (Video Clip) (4.83 MB). This time-lapse movie (at a rate of 5 frames per second) shows a chick embryo in SC that developed signs of cardiac failure and died on day 7. The embryo shows a normal development of the extraembryonic vasculature until day 7 after incubation. However, on the 7th day, it developed signs of cardiac failure (congested organs and peripheral vascular stasis caused by central pooling) within a few hours and died in end-stage heart failure with decompensated cardiac function.
• Movie III - (Video Clip) (8.54 MB). This time-lapse movie (at a rate of 5 frames per second) shows another chick embryo in SC that developed signs of cardiac failure (as described in movie II) and died at the end of day 7 after incubation.
• Movie IV - (Video Clip) (4.71 MB). This time-lapse movie (at a rate of 5 frames per second) shows another chick embryo in SC that developed signs of cardiac failure (as described in Movie II) and died on day 5 after incubation.